PROJECT SUMMARY/ABSTRACT Lifespan of major model organisms can be extended by dietary, pharmacological and genetic interventions. This includes mouse models, for which there are currently more than 15 known longevity interventions. However, these treatments have been identified on a case-by-case approach. The relationship between them is unclear and it is not known if they act through the same or different mechanisms and which interventions are most effective and robust. Accordingly, there is a need for systematic, unbiased identification of longevity interventions in mammals. To transition from extending lifespan in mice to doing this in humans, it is important to both identify many interventions that extend lifespan and define general principles of lifespan control. In this regard, the potential of the cell or organism to live a shorter or longer life is represented by it?s metabolic state, which in turn is reflected in it?s transcriptome. An intervention that adjusts the transcriptome in a certain way may shift an organism from a shorter-lived to a longer-lived state. We define such changes in gene expression as longevity signatures and have described them for (i) liver, kidney and brain across mammals differing 30- fold in lifespan; (ii) interventions known to extend lifespan in mice; and (iii) human cell types differing in cell turnover. Using these signatures, we then predicted and validated compounds with potential for lifespan extension. We propose to directly test these candidate longevity interventions in mice for the effect on lifespan and extend this approach to define principles of lifespan control based on advanced longevity signatures and identification of additional longevity interventions. Accordingly, we propose two broad research directions: (i) Identification and validation of longevity interventions in mice. We will first test 50 compounds for the effect on biological age in mice and then will test the 20 best-performing compounds for the effect on lifespan. We will also analyze successful longevity interventions with regard to mechanisms and pathways they target, and integrate this information to define principles of lifespan control. (ii) Platform for unbiased identification of interventions that extend lifespan. We will first develop advanced longevity signatures, based on the analyses of gene expression, metabolite profiling and their integration across three models of increased lifespan (longevity of mammals, longevity of cell types, and mouse interventions). Then, the signatures will be used to predict compounds that extend lifespan, which will be validated through gene expression and assays of biological age. Finally, we will build a platform for screening of compounds and other interventions and identify a broad range of longevity interventions. At the completion of the project, we will know which longevity signatures are best predictors of lifespan-extending interventions, identify pathways that mediate their effects, understand how lifespan is regulated, develop a platform for the identification of longevity interventions, and identify a number of new agents that slow mouse aging. With this information, tests can be designed for future testing of longevity interventions in humans.